Robust approach for attitude tracking and nonlinear disturbance rejection of rigid body spacecraft

Abstract

This paper studies the attitude tracking and nonlinear external disturbances rejection problem of rigid body spacecraft by a robust state feedback control law motivated by nonlinear internal model design. This control law, independent of inertia matrix, can not only achieve asymptotic tracking of the desired attitude, but also reject nonlinear external disturbances in the control torque, generated by a so-called nonlinear exosystem. It is also worth mentioning that our control law is a much simpler and smooth one, which can beat the inherent drawback of a discontinuous one that might result in undesired chattering effect in the real applications. With the introduction of nonlinear internal model, we convert the attitude tracking and disturbance rejection problem of spacecraft to the global robust stabilisation problem of a complicated nonlinear multi-input, multi-output augmented system, and then perform a rigorous and sophisticated stability analysis of such nonlinear augmented system. Simulation results will also be provided to demonstrate the effectiveness of our design.